Excerpt from Spatial Neglect

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Background

Spatial neglect is a behavioral syndrome occurring after brain injury. Spatial neglect involves the inability to report, respond, or orient to stimuli, generally in the contralesional space.¹ The authors have suggested that spatial neglect should also be defined by functional disability.² The deficit must not be fully attributable to primary sensory deficits (eg, hemianopia) or motor disturbance (eg, hemiparesis).

Treatment for spatial neglect focuses on cognitive rehabilitation that uses specific exercises and alterations to the patient's environment.

Despite the fact that speech and language, memory, and other cognitive abilities may be spared in brain-injured patients with spatial neglect, the prognosis for recovery of independent function in the patients with persisting spatial neglect is worse than in those with these other, seemingly more disabling, deficits.³ Even global aphasia and right hemiparesis may not have as great an effect on the ability to become independent.⁴

Although patients might recover from spatial neglect, they often remain severely disabled. Unfortunately, the reasons for the persistent disability are poorly understood. However, this dissociation might be explained by an overly narrow clinical definition for the presence of spatial neglect. Daily life functions are often performed under more challenging conditions than is the case for formal neuropsychological testing (eg, distractions, need for dual or multitasking, continuous dynamic computations using output from previous operations, need for self-initiation and self-organization) and may involve larger areas of space than a paper-and-pencil task on a tabletop (eg, navigating in an airport or mall, playing baseball, driving).

Spatial neglect also encompasses a cluster of symptoms, affecting several areas of vital importance in daily life, and is associated with other cognitive dysfunction such as emotional processing dysfunction and abnormal awareness of deficits (anosognosia and anosodiaphoria), which may affect independence.¹

Pathophysiology

People with injury to either side of the brain may experience spatial neglect, but neglect occurs more commonly in those with brain injury affecting the right cortical hemisphere, often causing left hemiparesis.⁵ Spatial neglect is more commonly associated with lesions of the inferior parietal lobule or temporoparietal region, superior temporal cortex, or frontal lobe. Less common are lesions of the subcortical regions, including the basal ganglia, thalamus, and cingulate cortex.^{6, 7, 1, 8} Spatial neglect may be more common and persistent after cortical than subcortical lesions.⁵

Because different neuroanatomic systems may be dysfunctional with spatial neglect, different neuropsychological mechanisms may explain the process of this disorder.

• Perception-attention: In the absence of primary sensory deficits, people with spatial neglect may have disordered awareness of events occurring in the neglected side.¹
• Imagery/representation: Even when no external stimuli are present, people with spatial neglect may have difficulty maintaining an internal map or image or other spatial knowledge pertaining to the environment, objects, body, or other reference frames.
• Self-monitoring: People with spatial neglect may be unaware of their deficit (anosognosia) or may be unconcerned about it (anosodiaphoria).
• Emotional processing: After a right-hemisphere stroke, individuals may have difficulty making appropriate emotional facial expressions and may lack normal affect or vocal intonation. At times, these signs can be mistaken for poststroke depression. Patients may also have difficulty representing emotional knowledge (disordered emotional semantics) or understanding emotional information presented via others' vocal prosody or facial expressions.
• Arousal: Hypoarousal may be associated with spatial neglect.
• Motor intentional deficits: These deficits include motor neglect and premotor neglect. People with spatial neglect may have trouble with activating or directing actions into portions of space. They might also be slow to act and not to persist.
• Personal neglect: Individuals may not normally attend to the left side of their bodies.

Frequency

United States

Reported overall frequency of spatial neglect is estimated to be anywhere from 13-81% in people who have had a right-hemisphere stroke, although 2 recent studies reported an overall rate of approximately 50%.^{5, 9} The frequency of spatial neglect may increase with the size of the lesion at presentation and at 3 months after injury.⁵

International

International frequency is not known.

Mortality/Morbidity

Spatial neglect may greatly increase morbidity and the risk of acute and chronic complications of stroke (eg, hip fracture). It is associated with a longer acute hospital stay.¹⁰

Race

Differences in the incidence or prevalence of spatial neglect associated with race have not been well investigated.

Sex

No compelling evidence currently indicates that spatial neglect is more common in men or in women.

Age

Spatial neglect may be more common in older individuals after stroke than it is in younger individuals, according to some preliminary evidence.^{11, 12, 5}

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